Circuit breaker with improved barrier means

ABSTRACT

An insulating-housing type circuit breaker is provided with openings in the housing to facilitate final trip adjustment after assembly of the breaker, and improved barrier means for closing the openings after the adjustment is made.

United States Patent 1 1 Ellsworth et al.

CIRCUIT BREAKER WITH IMPROVED BARRIER MEANS inventors: James P. Ellsworth, Beaver; Nick Yorgin, Ambridge, bothof Pa.

Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

Filed: June 1, 1972 Appl. No.: 258,593

U.S. Cl 337/20, 337/70, 337/82, 337/94, 337/112, 335/176 Int. Cl. H0lh 61/08 Field of Search 337/20, 70, 82, 83, 337/84, 94, 112, 347, 349, 380, 392, 398;

References Cited UNITED STATES PATENTS 4/1971 Ellsworth 335/176 1 July 24, 1973 3,617,970 11/1971 (Obayashi 337/70 x 3 3,258,563 6/1966 Landau 2,786,113 3/1957 Norden 2,642,509 6/1953 c616 6161. 337/82 Primary Examiner-Hemard A. Gilheany Assistant Examiner-A. T. Grimley Attorney- A. T. Stratton, W. A. Elchik et al.

[57] ABSTRACT An insulating-housing type circuit breaker is provided with openings in the housing to facilitate final trip adjustment after assembly of the breaker, and improved barrier means for closing the openings after the adjustment is made.

9 Claims, 5 Drawing Figures PAIENIED M24197?) sum 1' or 2 FIG! PAIENIEUJULMIQB SHEEI 2 (IF 2 CROSS-REFERENCE TO RELATED APPLICATIONS The circuit breaker disclosed herein is the type of circuit breaker disclosed in the application of Nick Yorgin et al., Ser. No. 11,452 filed Feb. 16, 1970 now US. Pat. No. 3,632,939.

BACKGROUND OF THE INVENTION It is old to provide a circuit breaker of the general type herein disclosed comprising a circuit-breaker mechanism mounted on an insulating base with an insulating cover secured to the base to enclose the circuitbreaker mechanism. For certain prior-art breakers the adjustment of the trip means was made prior to the time that the cover was secured to the base, and after the cover was secured the breaker was tested to determine if the breaker tripped properly in response to overload currents. If the test showed that the breaker did not trip at the right overload currents, the cover was then removed and the trip means was adjusted whereupon the cover was replaced and the breaker tested again. This process was repeated until the breaker tested properly with the cover secured in place. There is provided by this invention an improved insulating-housing type circuit breaker having opening means in the housing to facilitate trip adjustment after the breaker is assembled with the cover secured in place, and improved barrier means for closing the opening means in the housing of the assembled breaker after the adjustment is made.

SUMMARYIOF THE INVENTION An improved circuit breaker is provided with an insulating housing comprising an insulating base and an insulating cover secured to the base to enclose a circuitbreaker mechanism that is supported on the base. The circuit-breaker mechanism comprises a pair of contacts and trip means operable automatically upon the occurrence of overload current conditions to effect opening of the contacts. The trip means comprises a bimetal disposed in proximity to one end wall of the housing with an adjusting screw mounted on the bimetal to facilitate adjustment of the trip means. The insulating housing has an opening in the end wall in proximity to the adjusting screw. The housing is formed with slot means therein at said opening, and improved barrier means is supported in the slot means closing the opening. The barrier means comprises a pair of separate barriers and holding means holding the separate barriers in an extended position in the slot means to prevent access to the adjusting screw through the opening. During the assembly of the circuit breaker, after the insulating cover is secured in place, the circuit breaker trip is tested. If the circuit breaker does not trip with the proper time delay at the tested overload current, a screwdriver is moved through the opening to rotate the adjusting screw to adjust the bimetal trip until the breaker trips properly. Thereafter, one of the barriers is moved upward to the extended position to close the opening, and

a tang portion on one of the barriers interlocks with the other barrier to maintain the barriers in the extended position closing the opening except for small openings in the barriers which serve to permit the venting of gases through the barrier means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end view, with parts broken away, of the multi-pole circuit breaker with the barrier means of two of the pole units in the extended position and with the barrier means of the third pole unit in the nonextended position. The solderless terminal connector is not shown in the third pole unit for the purpose of clary;

FIG. 2 is a side sectional view, with parts broken away, taken generally along the line lI-II of FIG. 1;

FIG. 3 is an exploded perspective view, with parts broken away, illustrating the improved barrier means of this invention;

FIG. 4 is a perspective view, with parts broken away, illustrating the barrier means in the non-extended position; and

FIG. 5 is a view similar to FIG. 4 illustrating the bar rier means in the extended position.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, there is shown, in FIGS. 1v and 2, a multi-pole molded-case or insulating-housing type circuit breaker 3. The circuit breaker 3 is of the type that is more specifically described in the copending application of Nick Yorgin et al., Ser. No. 11,452 filed Feb. 16, 1970 and in the US. Pat. to Nick Yorgin et al., No. 3,460,075. Thus, only a brief description of the circuit breaker is provided herein. The circuit breaker comprises an insulating housing 5 and a circuit breaker mechanism 7 supported in the housing 5. The housing 5 comprises a molded insulating base 9 and a molded insulated cover 11 secured to the base 9 by means of four bolts 12 to enclose the circuit breaker mechanism that is mounted on the base 9. The insulating housing 5 will be hereinafter more specifically described.

The circuit breaker mechanism 7 comprises an operating mechanism 13 and a latch mechanism 15. The circuit breaker mechanism also comprises a trip device 17 for each of the three pole units of the circuit breaker.

A stationary contact 19, a movable contact 21 and an arc-extinguishing unit 23 are provided for each pole unit of the circuit breaker. The movable contact 21 is mounted on a movable contact arm 25 that is pivotally connected to a switch arm 26 that is secured to an insulating common tie bar 27. The tie bar 27 is supported for pivotal movement about the elongated axis thereof. A toggle, comprising a toggle link 29 and a toggle link 31, is pivotally connected at one end thereof to the movable switch arm 26 of the center pole unit and at the other end thereof to a latched trip member 33 that is pivotally supported on a pin 35 that is mounted between a pair of supporting plates 37. An operating tension spring 39 is connected at one end thereof to the knee pivot 41 of the toggle and at the other end thereof to the bight portion of an inverted generally U-shaped operating member 43. A handle 45 extends from the lever 43 through an opening in the front of the housing cover 11 to permit manual operation of the breaker.

The releasable trip member 33 is latched at the free end thereof by means of a roller latch member 47 that is in turn latched by an elongated insulated trip bar 49 that is mounted for pivotal movement about the elongated axis thereof. The operating lever 43 is an inverted U-shaped lever that is mounted at the ends of the legs thereof in U-shaped notches in the supporting plates 37.

The circuit breaker is manually operated by operation of the handle 45 from the open position seen in FIG. 2 in a clockwise direction to the closed position during which movement the line of action of the spring 39 is moved to the right to erect the toggle 29, 31 to pivot the movable switch arm 26 of the center pole unit in a clockwise direction to the closed position.

The breaker is manually opened by reverse movement of the handle 45 in a counterclockwise direction to the open position during which movement the line of action of the spring 39 is moved to the left to collapse the toggle 29, 31 to thereby move the switch arm 26 of the center pole unit to the open position seen in FIG. 2.

Since all three of the switch arms 26 for the three pole units of the three-pole circuit breaker are fixed to the common tie bar 27, operation of the center-pole switch arm 26 to the closed and opened positions simultaneously operates all three of the switch arms 26 to the closed and opened positions.

The circuit breaker is thermally tripped by operation of the trip device 17 for any of the pole units. In each pole unit the trip device 17 comprises an elongated current carrying bimetal 51 having an adjusting screw 53 mounted thereon. The generally L-shaped bimetal 51 is secured to the base 9 by means of a bolt 54. The circuit in each pole unit of the multi-pole circuit breaker extends from a terminal connector 57 through a conductor 58, the contact 19, the contact 21, the contact arm 25, a flexible conductor 59, the bimetal 51, a flexible conductor 61, a conducting member 63, to a terminal connector 65.

Upon the occurrence of an overload above a first predetermined value, the bimetal 51 becomes heated and flexes to the right (FIG. 2) whereupon the screw 53 engages the trip bar 49 to rotate the trip bar 49 in a counterclockwise direction whereupon the trip bar 49 releases the latch 47. Upon release of the latch 47, the spring 39, operating through the toggle 29, 31, pivots the trip member 33 in a clockwise direction with the latch 47 moving in a clockwise direction about its pivot 71. This movement changes the line of action of the spring 39 whereupon the spring collapses the toggle 29, 31 to move the movable switch arm 26 to the open position. During the tripping operation, the spring 39 moves the handle 45 to a position intermediate the ON" and OFF positions to provide a visual indication that the breaker has tripped. Following a tripping operation, the breaker is reset by movement of the handle 45 in a counterclockwise direction to a position slightly past the full "OFF" position. During this movement, a projection 73 on the operating member 43 engages a shoulder on the trip member 33 to rotate the trip member 33 in a counterclockwise direction during which movement the trip member 33 engages the latch 47 to move the latch to the latching position, and a spring 77 moves the trip bar 49 to the latching position so that upon release of the handle 45 the breaker will be latched in the reset position seen in FIG. 2. Thereafter, the circuit breaker can be manually operated in the same manner as was hereinbefore described.

The circuit breaker is magnetically tripped by operation of an electromagnet that comprises a stationary magnetic member 81 and a movable magnetic armature 83 that is supported for pivotal movement by means of a pair of pivot arm supports 85. The current in the bimetal 51 energizes the magnetic members 81, 83. Upon the occurrence of a severe overload above a second predetermined value the armature 83 is pivotally attracted to the magnetic member 81 whereupon a part of the armature above the pivot support 85 thereof engages the trip bar 49 to rotate the trip bar 49 in a counterclockwise direction to effect an instantaneous magnetic tripping operation. A shunt conductor 86 on the armature 83 is utilized to shunt current through the stationary magnetic member 81 to the conductor 63 to thereby shunt current past the bimetal upon the occurrence of a magnetic tripping operation to protect the bimetal against excessive heating. The circuit interrupter is reset following an instantaneous magnetic tripping operation in the same manner as was hereinbefore described following the time delay thermal tripping operation.

The insulating base 9 is a molded insulating member molded with integral barriers that cooperate with barriers that are molded integral with the insulating cover 11 to separate the housing 5 into three adjacent poleunit compartments in a manner more specifically described in the above-mentioned application of Nick Yorgin et al. Ser. No. 11,452. The base and cover engage each other at a generally planar engagement as shown by the lines 89 in FIGS. 1 and 2. As can be understood with reference to FIGS. 1 and 2, the housing is formed with three external cavities 91 at each end of the circuit breaker for the solderless terminal connectors 57, 65 in a well known manner. The insulating base 9 is formed with a pair of slots 93 (FIG. 3) for each pole unit at one end wall of the circuit breaker, and the housing is provided with a separate opening 95 in the end wall for each pole unit to provide access to the associated adjusting screw 53. Barrier means 97 is provided in each pole unit supported in the associated slots 93. Each of the barrier means 97 comprises a lower barrier 101 and an upper barrier 103. Each of the barriers 101 and 103 is a relatively stiff insulating or metal member with the upper barrier 103 being formed with a tang portion 105 formed as a part thereof to provide interlocking means to interlock with the lower barrier 101 in a manner to be hereinafter described. During assembly of the breaker, each of the barrier means 97 is disposed in the associated slots 93 such that the barriers 101 and 103 are in a face-to-face non-extending position as shown in FIG. 4 and in the right-hand pole unit in FIG. 1. With the barriers in the non-extended position, the cover 11 is mounted on the base 9 by means of the mounting screws 12 (FIGS. 1 and 2) and the circuit breaker is given a final test to determine whether the breaker thermally trips at the desired current level and with the desired time delay. If any of the pole units does not thermally trip at the desired current level with the desired time delay, the associated adjusting screw 53 is rotated to adjust the trip for proper operation. When the tests of all three pole units are successful, each of the barriers 101 is raised, by means of a suitable tool, from the non-extended position seen in FIG. 4 (and in the one pole unit in FIG. 1) to the extended position seen in FIG. 5 (and in the two other pole units in FIG. 1) during which movement the resilient tang 105 of each of the barriers 103 interlocks with a cooperating surface on the associated barrier 101 to maintain the barriers 101, 103 in the extended position thereby closing the openings through which the tool was extended for adjusting the screws 53. If desired, a dab of cement could be placed at the junction between the barriers 101, 103-to more securely fix the barriers 101, 103 in the extended position. The barriers 101, 103 are provided with openings 107, 109 (FIG. 5) respectively to vent gases from the internal compartments of the circuit breaker during circuit interruption.

From the foregoing, it can be understood that there is provided by this invention an improved insulatinghousing type circuit breaker with openings in the housing to facilitate final trip adjustment after the assembly of the breaker and after the cover is secured to the base, which circuit breaker comprises improved barrier means for closing the openings after the final adjustment is made.

We claim:

1. A circuit breaker comprising an insulating housing, a circuit-breaker mechanism supported in said insulating housing, said circuit-breaker mechanism com prising a pair of contacts and trip means operable automatically upon the occurrence of overload current conditions to effect opening of said contacts, said trip means comprising an adjusting structure adjustable to adjustsaid trip means, said insulating housing having an opening therein in proximity to said adjusting structure, said insulating housing having slot means therein at said opening, barrier means supported in said slot means closing said opening, said barrier means comprising a pair of separate barriers and holding means holding said separate barriers in an extended position in said slot means preventing access to said adjusting structure through said opening.

2. A circuit breaker according to claim 1, said separate barriers comprising an upper barrier and a lower barrier, and said upper barrier being disposed adjacent said adjusting structure to prevent access to said adjusting structure through said opening.

3. A circuit breaker according to claim 1, and said adjusting structure comprising an adjusting screw rotatable to adjust said trip means.

4. A circuit breaker according to claim 1, and said holding means comprising interlocking means on said barrier means.

5. A circuit breaker according to claim 2, and said holding means comprising interlocking means on said barrier means.

6. A circuit breaker according to claim 5, and said interlocking means comprising a tang on said upper barrier engaging said lower barrier to maintain said barrier means in said extended position.

7. A circuit breaker according to claim 6, each of said separate barriers being a relatively stiff member, and said tang being formed integral with said upper barrier.

8. A circuit breaker according to claim 7, and said barrier means having venting-opening means therein for venting gases out of said housing.

9. A circuit breaker according to claim 8, said trip means comprising a bimetal member, said adjusting screw being supported on said bimetal member, upon the occurrence of said overload current conditions said bimetal member flexing and moving said adjusting screw to actuate said trip means to effect automatic opening of said contacts, and said adjustment being made by rotation of said adjusting screw on said bimetal member. 

1. A circuit breaker comprising an insulating housing, a circuit-breaker mechanism supported in said insulating housing, said circuit-breaker mechanism comprising a pair of contacts and trip means operable automatically upon the occurrence of overload current conditions to effect opening of said contacts, said trip means comprising an adjusting structure adjustable to adjust said trip means, said insulating housing having an opening therein in proximity to said adjusting structure, said insulating housing having slot means therein at said opening, barrier means supported in said slot means closing said opening, said barrier means comprising a pair of separate barriers and holding means holding said separate barriers in an extended position in said slot means preventing access to said adjusting structure through said opening.
 2. A circuit breaker according to claim 1, said separate barriers comprising an upper barrier and a lower barrier, and said upper barrier being disposed adjacent said adjusting structure to prevent access to said adjusting structure through said opening.
 3. A circuit breaker according to claim 1, and said adjusting structure comprising an adjusting screw rotatable to adjust said trip means.
 4. A circuit breaker according to claim 1, and said holding means comprising interlocking means on said barrier means.
 5. A circuit breaker according to claim 2, and said holding means comprising interlocking means on said barrier means.
 6. A circuit breaker according to claim 5, and said interlocking means comprising a tang on said upper barrier engaging said lower barrier to maintain said barrier means in said extended position.
 7. A circuit breaker according to claim 6, each of said separate barriers being a relatively stiff member, and said tang being formed integral with said upper barrier.
 8. A circuit breaker according to claim 7, and said barrier means having venting-opening means therein for venting gases out of said housing.
 9. A circuit breaker according to claim 8, said trip means comprising a bimetal member, said adjusting screw being supported on said bimetal member, upon the occurrence of said overload current conditions said bimetal member flexing and moving said adjusting screw to actuate said trip means to effect automatic opening of said contacts, and said adjustment being made by rotation of said adjusting screw on said bimetal member. 